General equation for press/shrink fit stress?

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SUMMARY

The discussion focuses on calculating shear stresses in a shrink fit assembly involving a cylindrical solid shaft and a cylindrical hub. The shaft's diameter exceeds the hub's hole diameter, leading to an interference fit created by cooling the shaft and heating the hub. The analysis confirms that shear stresses do not occur in either component; instead, the stress is primarily hoop stress, as derived from Roark's equations. The relevant equations include the radial displacement formula, ΔR = qR² / Et, and the hoop stress formula, σ₂ = qR / t.

PREREQUISITES
  • Understanding of shrink fit assembly mechanics
  • Familiarity with hoop stress and meridional stress concepts
  • Knowledge of Roark's equations for stress analysis
  • Basic principles of thermal expansion and contraction
NEXT STEPS
  • Study Roark's Formulas for Stress and Strain for detailed stress analysis
  • Learn about thermal expansion coefficients for different materials
  • Explore finite element analysis (FEA) software for simulating shrink fit assemblies
  • Investigate the effects of varying interference on stress distribution in assemblies
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Mechanical engineers, materials scientists, and anyone involved in designing or analyzing shrink fit assemblies will benefit from this discussion.

cowpuppy
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Shear stresses in shrink fit assembly?

I'm trying to figure out what shear stresses there would be from a shrink fit assembly, if any. You have a cylindrical solid shaft and a cylindrical hub, where the shaft diameter is greater than the hub's hole diameter. The shaft cooled and thus shrunk and the hub is heated and expanded so they will fit together, then allowed to come back to the original temperature.

Will either the shaft or cylindrical hub experience any shear stresses?
 
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Basically you can use superposition to find this. There is an interference, call it e. You can find the pressure which would cause that expansion e. The stress in the shaft from the interference will then be the stress caused from that pressure.

It should be all hoop stress if I'm not mistaken. Looked it up, from Roark, you have the radial displacement
<br /> \Delta R = \frac{qR^2}{Et}<br />
The idea is then to find q that causes your interference R. Then your meridional stress is zero, while your hoop stress is
<br /> \sigma_2 = \frac{qR}{t}<br />

Good luck,
 

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